/**
 * Aggregates all elements from the source iterable into a single value using the provided accumulator.
 *
 * @typeParam T - Element type produced by the source iterable.
 * @typeParam TOut - Accumulator result type yielded after processing the entire sequence.
 * @param src - Source iterable whose elements will feed into the accumulator function.
 * @param seed - Initial accumulator value supplied to the first call of `aggFunc`.
 * @param aggFunc - Combiner invoked with the previous accumulator, current element, and current index.
 * @returns The final accumulator value after iterating through the entire source.
 *
 * @example
 * ```ts
 * const total = _aggregate([1, 2, 3], 0, (acc, n) => acc + n);
 * console.log(total); // 6
 * ```
 *
 * or using the curried version:
 * ```ts
 * const total = pipeInto(
 *   [1, 2, 3],
 *   aggregate(0, (acc, n) => acc + n)
 * );
 * console.log(total); // 6
 * ```
 */
export declare function _aggregate<T, TOut>(src: Iterable<T>, seed: TOut, aggFunc: (prev: TOut, curr: T, idx: number) => TOut): TOut;
/**
 * Curried version of {@link _aggregate}.
 */
export declare const aggregate: <T, TOut>(seed: TOut, aggFunc: (prev: TOut, curr: T, idx: number) => TOut) => (src: Iterable<T>) => TOut;